Validity of Self-reported Endometriosis

A Comparison Across Four Cohorts

A.L. Shafrir; L.A. Wise; J.R. Palmer; Z.O. Shuaib; L.M. Katuska; P. Vinayak; M. Kvaskoff; K.L. Terry; S.A. Missmer

Disclosures

Hum Reprod. 2021;36(5):1268-1278. 

In This Article

Materials and Methods

Participant Populations

To assess the validity of self-reported endometriosis, medical records were obtained for participants of the following four cohorts who had reported endometriosis on self-administered questionnaires: the Black Women's Health Study (BWHS), Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l'Education Nationale (E3N)––often referred to in the USA as the 'French Teachers' Cohort', Growing Up Today Study (GUTS), and Nurses' Health Study II (NHSII). In all four cohorts, women (or a subset of women as described below and in Table I) who reported an endometriosis diagnosis on a self-administered questionnaire (see Supplementary Data for cohort-specific questions) were contacted by cohort staff to confirm their report and to provide consent to release pertinent medical records. We evaluated the accuracy of reporting 'Yes' to having been diagnosed with endometriosis. No cohort attempted to collect medical records from participants who never reported that they had been diagnosed with endometriosis, although all cohorts asked the participants repeatedly at an interval of a minimum of every 2 years whether they had been diagnosed with endometriosis. None of the cohorts included a question on undergoing a laparoscopy or laparotomy except for in the context of confirmation of endometriosis by laparoscopic surgery. Therefore, it would be logistically and financially infeasible to obtain medical records to validate 'never' report of endometriosis among the full cohorts.

Black Women's Health Study. The BWHS is an ongoing, prospective cohort study that began in 1995 when 59,001 self-identified black women aged 21–69 years living within the USA were recruited from the subscription list of Essence magazine and black professional organizations (Rosenberg et al., 1995; Russell et al., 2001). At baseline, participants completed self-administered postal questionnaires to collect data on demographic, lifestyle, and behavioral factors; reproductive and medical history; and medication use. Participants then completed follow-up questionnaires every 2 years following enrollment to update outcome, exposure, and covariate data. From 1995 onward, participants were asked to report any diagnosis of endometriosis. From 1999 onward, participants who reported an endometriosis diagnosis were additionally asked about confirmation by laparoscopic surgery. From 2008 through 2016, all participants of reproductive age who reported an incident diagnosis of endometriosis between baseline (1995) and 2013 (n = 1605) were re-contacted to confirm their diagnosis and to consent for study staff to procure portions of their medical record pertinent to endometriosis and its diagnosis. For participants who provided consent for procurement and review of their medical record, study staff attempted to contact the treating physician and/or hospital to obtain all relevant medical records. This study was approved by the Institutional Review Board of Boston University Medical Campus.

Etude Epidémiologique Auprès de Femmes de la Mutuelle Générale de l'Education Nationale. The E3N study is a French prospective cohort study involving 98,995 French women born between 1925 and 1950 and insured by a national health plan primarily covering teachers (Clavel-Chapelon and E3N Study Group, 2015). Participants were enrolled from February 1, 1989 through November 30, 1991 after returning a self-administered questionnaire on lifestyle and medical history and a signed consent form. Follow-up questionnaires are sent every 2–3 years to update lifestyle and medical information. In 1992, when these women were age 42 to 67 years, participants reported if they had ever been diagnosed with endometriosis; information on endometriosis diagnosis was updated at each subsequent questionnaire cycle through 2008. Between 1990 and 2005, 558 participants reported that they had an incident endometriosis diagnosis, and in 2006, 200 of these participants were randomly selected to confirm their diagnosis and to provide their hospital and pathology records related to endometriosis, along with the contact details of their physicians. A participant's physician was contacted if the participant could not find her medical records or questions arose while abstracting from the medical records received to seek a definitive confirmation. The E3N cohort received ethical approval for the study from the French National Committee for Computerized Data and Individual Freedom (Comité National Informatique et Libertés, CNIL).

Nurses' Health Study II. The NHSII is an ongoing, prospective cohort study. A total of 116,429 women aged 25–42 years and living in one of 14 states in the USA were enrolled in 1989—all were registered nurses. Through self-administered questionnaires, participants provided information on demographic, lifestyle, anthropometric, reproductive, and medical factors at baseline and biennially. Starting in 1993, participants were asked to report on each questionnaire if they had been diagnosed with endometriosis and whether that diagnosis was confirmed by laparoscopy. Two endometriosis validation studies within the NHSII have been performed. In the first wave in 1994, a random sample of 200 women from the 1,766 who had self-reported an incident diagnosis of endometriosis between 1989 and 1993 were contacted to confirm their report and consent to procurement of their pertinent medical records for review (Missmer et al., 2004). In the second wave, from 2009 through 2011, all participants who reported a diagnosis of endometriosis between 1989 and 2007, were not part of the first validation study, and were members of the NHSII nested blood sample cohort (n =711) (Tworoger et al., 2006) were contacted to confirm their endometriosis diagnosis and consent to procurement of the pertinent portions of their medical records for review. The relevant physicians and/or hospitals were contacted to obtain these medical records. The study protocol was approved by the Institutional Review Boards of Brigham and Women's Hospital and the Harvard T.H. Chan School of Public Health.

Growing up Today Study. GUTS is an ongoing, prospective cohort of 27,706 women and men (n =15,044 women) living in the USA. The first stage of the cohort (GUTS1) began in 1996 with the recruitment of girls and boys, then aged 9–14 years, who are children of women in NHSII. In 2004, a second group of GUTS participants, then aged 10–17 years, were also enrolled (GUTS2). All participants completed baseline questionnaires and annual or biennial follow-up questionnaires on demographics, lifestyle factors, and reproductive and medical history. Starting in 2005, female participants were asked to report on each questionnaire if they had been diagnosed with endometriosis and if their diagnosis was confirmed by laparoscopy. All participants who had reported ever being diagnosed with endometriosis on questionnaires between 2005 and 2016 were contacted to confirm their diagnosis and obtain consent to procure the pertinent portions of their medical records for review (n =380). The relevant physicians and/or hospitals were contacted to obtain these medical records. The study protocol was approved by the Institutional Review Boards of Brigham and Women's Hospital and the Harvard T.H. Chan School of Public Health.

Medical Record Abstraction

For all four cohorts, cohort-specific trained investigators and/or physicians abstracted information about endometriosis from the medical records using standardized forms designed for and specific to each cohort. For the validation component, these standardized forms captured: if the medical records received were missing records deemed relevant to endometriosis (e.g. no information from a primary care physician, surgeon, or gynecologist; no information on gynecologic conditions or review of gynecologic issues); evidence of surgery for suspected endometriosis; noted visualization of endometriosis at surgery; and availability of pathology report findings. Endometriosis reported on the self-administered questionnaire was classified as confirmed if documentation of endometriosis was found in any of the physician, surgical, or pathology records. Participants were further classified according to the source of endometriosis documentation. Participants were classified as having a clinical diagnosis of endometriosis if there was documentation of a physician diagnosis of endometriosis without evidence of a surgical evaluation. Surgically confirmed endometriosis was noted if there was evidence of a surgical evaluation and a report that a surgeon had visualized endometriosis during a laparoscopy, laparotomy, or hysterectomy (regardless of surgical modality). If a pathology report was available, documentation of endometriosis and/or the identification of endometrium-like glands or stroma were classified as histologically confirmed endometriosis. Participants for whom endometriosis was not noted as having been visualized during surgery but for whom the pathology report documented endometriosis were also classified as histologically confirmed, but it was noted that endometriosis had been erroneously absent from the surgical record. In the first and second NHSII waves and GUTS, additional information on AFS (The American Fertility Society, 1979, 1985) or rASRM (American Society for Reproductive Medicine, 1997) stage and the presence or absence of endometrioma(s) or deep endometriosis (NHSII second wave and GUTS only) were also abstracted.

Statistical Analyses

For each cohort, we calculated overall confirmation of self-reported endometriosis (i.e. positive predictive value) as the proportion of participants with any medical record documentation of endometriosis (i.e. those with a clinical, surgical, or histologic diagnosis) divided by the total number of participants for whom relevant medical records were obtained. Additionally, we assessed the proportion of participants with surgical confirmation and the proportion with histologically confirmed endometriosis out of participants with surgical and/or pathology records available. Finally, we calculated the proportion of participants with clinical confirmation (i.e. a clinician had told them they have endometriosis) out of participants without evidence of surgery. In secondary analyses within BWHS, GUTS, and NHSII, we assessed the surgical and physician confirmation proportions separately for those who reported that they had laparoscopic confirmation of endometriosis and those who did not report that their diagnosis had included laparoscopic confirmation. Additionally, in NHSII second wave, we assessed the overall and surgical confirmation proportions separately for those with concurrent infertility and those who never reported infertility, as we hypothesized a priori that women with concurrent infertility may recall their endometriosis diagnosis more accurately than women who never experienced infertility. Concurrent infertility included women who reported undergoing an infertility evaluation in the same follow-up cycle as their self-reported endometriosis diagnosis. Analyses were performed using SAS 9.4 (Cary, NC, USA).

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